Reovirus is a dsRNA virus with tropism to cancer cells having an activated Ras pathway. It has been demonstrated that administration of reovirus into tumor bearing animals results in generation of a robust anti-viral response mediated by both the humoral and cellular arms of the immune system. This anti-viral response can antagonize the oncolytic effectiveness of the therapeutic virus. As such, combinational use of immune suppressing agents to overcome this immune antagonism of reovirus oncolysis has been explored. It has been demonstrated that co-administration of agents that ablate the generation of neutralizing anti-reovirus antibodies (NARA) can result in morbidity in the test animals. The response in the test animals has been characterized by reovirus replication outside of the target tumor tissues, suggesting that humoral immunity serves a protective role in preventing reovirus infection of the host (Qiao et al., Clin. Cancer Res. 14(1):259-69 (2008)).